The present disclosure pertains to an aqueous inkjet ink containing an 1-alkyl-2-pyrrolidione, an anionic surfactant, a pigment colorant, and a polymeric binder. The present disclosure further pertains to an ink set containing this aqueous inkjet ink, as well as to methods of printing with this ink and ink set on a variety of substrates and particularly nonporous media.
Digital printing methods such as inkjet printing are becoming increasingly important for printing markets other than the desktop printing for the small office/home office market. The desktop printing market category is based upon the use of inks that have been optimized primarily for printing documents and photographs. Commercial printing applications range from printing wide format posters, banners, and billboards, to product coding on cans and bottles. For present purposes, the printing of wide format graphics will be considered as commercial graphics. Industrial printing applications include direct mail, addressing, product coding, and marking. High speed, page wide array industrial inkjet-based printers are also in use to print magazines, newspapers, etc. In addition, a new field of commercial printing is the printing of books on demand in a book store setting.
The inks used in those commercial/industrial applications have different requirements. In the desktop market, the print droplet must be tightly controlled. Additionally, desktop printers print on limited types of substrates. In commercial and industrial printers, on the other hand, a high premium is often placed on being able to print on a wide range of substrates. Industrial inkjet printing is an established, expanding market. Inkjet printers are widely used to place images on mail and business forms, on primary and secondary packaging. Also, the time for the printed image to dry is much more important for these commercial/industrial printers.
The substrates range from porous substrate like newspaper media, uncoated bond papers used to print books and transpromotional material to nonporous media used to print magazines and marketing literature.
Printing of non-porous media is particularly challenging because they can be coated with a polymeric coating such as styrene/butadiene copolymers, polyvinyl alcohols etc. These polymeric coating make the media very hydrophobic. It can be difficult to wet such media with aqueous ink. It is also difficult to dry the media after printing the aqueous inks. The drying problem is made worse due to the high speeds at which commercial inkjet web presses operate. Finally, after drying the printed image/printed text must permanently adhere to the coated offset (nonporous) media such that the ink is not smudged off in regular use.
The durability requirements for commercial/industrial printing dictate the use of pigments in preference to dyes. These pigments provide better, longer lasting and more durable printed images.
A need exists for highly stable, higher-quality and different property inks for ink-jet applications.